With the development of network communication, the urge to provide more data transmission services stimulates an ever-growing demand for increase of network communication bandwidth. Replacing conventional metal wires with optical fibers in wire communication modules for network communication among servers can not only increase the network communication bandwidth, but also lower energy consumption attributed to data transmission. Moreover, the volume of the wire communication modules can also be reduced. Recently, to further reduce the volume of the wire communication modules, multi-channel optical fiber couplers are adopted accordingly to substitute single-channel optical couplers.
In U.S. Pat. No. 6,888,988, No. 8,283,678, and No. 8,457,457, conventional one-piece optical couplers are disclosed for directing a light beam from a light source into an optical fiber. Such conventional optical couplers may be able to, by virtue of the configuration/structure thereof, split the light beam into multiple parts including, e.g., a first part to propagate along a first optical path to be received by the optical fiber, and a second part to propagate along a second optical path to be received by a photo detector for detecting and monitoring the light power thereof. Since a power ratio among the parts of the light beam usually remains constant, the light power of the first part can be calculated from that of the second part detected by the photo detector, thereby allowing power adjustment of the light source to provide a relatively stable power input for the optical fiber. However, such one-piece conventional optical fiber couplers require delicate manufacturing processes and thus have relatively high production costs and relatively low product yields.
U.S. Pat. No. 8,503,838 discloses a two-piece conventional optical fiber coupler, where a component of such conventional optical fiber coupler may be provided with an optical coating for lowering the output power of the light beam to be received by the optical fiber. Although it is relatively simple to manufacture each component of the conventional optical fiber coupler in comparison with the aforesaid one-piece optical fiber couplers, both components still have three-dimensional structures, such as grooves or convex surfaces which are relatively difficult to form, and the assembling tolerance becomes an important factor that affects the reliability of the same.
In U.S. Pat. No. 8,787,714, there is disclosed a three-piece conventional optical fiber coupler which further includes a main body, a prism, and a light filter which can be replaced for adjusting the output light power. However, adhesives are required for connecting the prism to the main body, and air bubbles in the adhesive may adversely affect the optical property of such conventional optical fiber coupler.